1. The Field of the Invention
The present invention relates generally to keypad devices, and more particularly, but not necessarily entirely, to a switch matrix which allows the use of variable key positions and key sizes on the keypad and to the use of such devices.
2. Background Art
It is common practice to provide keypads consisting of one or more keys arranged for entry of data or performing functions such as activating switches. Keypads are used for various types of electronic devices such as user interfaces for home automation and security systems, calculators, telephones, etc. Keypads commonly include an assembly of various parts maintained in a housing.
For example, FIG. 1 shows a keypad, generally indicated at 2, known in the art for use as a primary control point for automation systems used in areas such as homes, businesses, boats, yachts, motor homes and busses. The keypad 2 includes a plurality of keys 8 which can be depressed to control systems such as lighting, security, audio visual and heating/cooling for example. The keys 8 are connected to electronic circuitry which is contained in a housing 4. The keys 8 are fixed in place by an attaching plate 6 so as to be non-removable from the keypad 2. The attaching plate 6 has apertures 7 through which the keys 8 protrude. The apertures 7 are sized and shaped to accommodate keys 8 of a particular size and shape. Therefore, a different attaching plate 6 is required for each size and shape of keys 8 used for the keypad 2. Furthermore, the location of the keys 8 is confined to the locations of the apertures 7. Therefore, a different attaching plate 6 must be used for different configurations of the keys 8. Moreover, if any of the keys 8 become damaged or require replacement, the entire keypad 2 must be replaced or the attaching plate 6 must be removed. Removal of the attaching plate 6 is a difficult task which may require the services of a professional or use of specialized equipment since the attaching plate 6 is fixed to the housing 4 and is not designed to be easily removed without damaging the attaching plate 6 or the housing 4.
The previously available devices are thus characterized by several disadvantages that are addressed by the present invention. The present invention minimizes, and in some aspects eliminates, the above-mentioned failures, and other problems, by utilizing the methods and structural features described herein.
In view of the foregoing state of the art, it would be an advancement in the art to provide a switch matrix which is capable of being used with keys of different sizes and shapes. It would be a further advancement in the art to provide a switch matrix which allows the keys to be arranged in different configurations using differing numbers of keys. It would also be an advancement in the art to provide a switch matrix which allows the keys to be easily installed and replaced without damaging the matrix.